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SUMMARY

Four groups of 18 beef calves each were used to evaluate effects of different treatments on parasite control and weight gains. The investigation extended from November 1986 (weaning) to October 1987. Group-1 calves were treated with ivermectin (200 μg/kg of body weight, SC) at approximately 6-week intervals for a total of 8 treatments; group-2 calves were given the same dosage of ivermectin by the same route of administration as group-1 calves in November, March, and July; group-3 calves were given fenbendazole paste (5 mg/kg, po) at the same times as group-2 calves; and group-4 calves served as untreated controls with provision for ivermectin salvage treatment. All groups grazed on individual pairs of larval-contaminated, 1.6-ha pastures. Highest (P < 0.05) initial worm counts in fall tracer calves were found in group 3 (Ostertagia ostertagi and Trichostrongylus axei adults) and group 4 (O ostertagi and Haemonchus adults). Fecal egg counts of group-1 calves were low throughout the experiment and pasture larval counts remained negligible after July. Egg counts and larval counts of other groups remained higher into summer. Worm counts, including O ostertagi inhibited early fourth-stage larvae (el 4), were highest (P < 0.05) in groups-3 and -4 spring tracer calves; numbers of O ostertagi el 4 were similarly high in groups 2, 3, and 4; and T axei counts were highest (P < 0.05) in groups-3 and -4 yearlings slaughtered in spring. Liveweights of group-1 calves were greater (P < 0.05) than in other groups from March 2 to October, and by July 2, group-2 calves had a liveweight advantage over group-4 calves. Group- 3 calves had the lowest rate of gain from March to July and mean liveweight of the group was less (P < 0.05) than in all other groups from April to October. Only minimal worm numbers were recovered from groups-1 or -2 calves in October. Large numbers of O ostertagi and T axei were recovered from group-4 calves and O ostertagi from group-3 calves. A few calves in groups 3 and 4, but particularly in group 4, were affected by type-II disease (chronic to acute gastritis caused by maturation and emergence of previously inhibited larvae) from August to October. Final mean liveweights in descending order were 365 kg in group 1, 328 kg in group 2, 316 kg in group and 281 kg in group 3.

Free access
in American Journal of Veterinary Research
in Journal of the American Veterinary Medical Association
in Journal of the American Veterinary Medical Association

Objective

To evaluate use of an assay for measuring serum concentration of canine thyroid-stimulating hormone (cTSH) as an aid for diagnosing thyroid disease in a population of dogs suspected of having hypothyroidism.

Design

Case-cohort study.

Animals

62 healthy dogs and 49 dogs with clinical signs consistent with hypothyroidism (16 were hypothyroid and 33 were euthyroid with concurrent disease).

Procedure

Samples from healthy dogs were used to establish a reference range for serum cTSH concentration. The 49 dogs were categorized as hypothyroid or euthyroid with concurrent disease on the basis of clinical signs, results of additional diagnostic and thyroid-stimulating hormone (TSH) response tests, and response to administration of levothyroxine sodium. Function of the thyroid gland was considered normal when serum total thyroxine (T4) concentration 6 hours after TSH administration was > 2.5 µg/dl. Hypothyroidism was diagnosed when serum T4 concentration after TSH administration was ≤ 1.5 µg/dl.

Results

Serum cTSH concentration differed significantly among all 3 groups. Four of 33 (12%) euthyroid dogs had cTSH concentrations that were greater than the reference range, whereas 6 of 16 (38%) hypothyroid dogs had cTSH concentrations within the reference range. Specificity for serum cTSH concentration was 0.88 and sensitivity was 0.63. When interpreted in combination with serum T4 concentration, specificity increased to 1.0.

Clinical Implications

cTSH assay had good specificity for use in the diagnosis of hypothyroidism in dogs. Because this assay had low sensitivity, a diagnosis of hypothyroidism could not be excluded on the basis of a serum cTSH concentration that was within the reference range. (J Am Vet Med Assoc 1998; 212:387-391)

Free access
in Journal of the American Veterinary Medical Association

Summary

Eighteen 4-week-old pigs were used in a study to evaluate tiamulin in drinking water for control of experimentally induced Streptococcus suis type-2 infection. Pigs in groups A and B (n = 6 pigs/group) were aerosolized with a logarithmic-growth phase culture of S suis type 2, whereas pigs in group C (n = 6 pigs) served as noninfected and nonmedicated controls. After exposure to S suis, pigs in group B were given 180 mg of tiamulin/L of drinking water for 5 days. Pigs in group B consumed more feed (P = 0.009) and gained body weight faster (P = 0.02) than did pigs in group A. Pigs in group A had higher rectal temperature (P = 0.05) for up to 7 days after S suis exposure, higher clinical sign scores (P = 0.008), higher serum cortisol concentration on days 7 and 14, higher gross lesion scores (P = 0.03), and higher microscopic lesion scores (P = 0.01) than did pigs in groups B and C. Gross and microscopic lesions in pigs of groups A and B included meningitis, pneumonia, pleuritis, pericarditis, peritonitis, and synovitis of variable severity. Streptococcus suis type 2 was recovered from tissue specimens of 2 group-A pigs and 1 group-B pig. Data indicated that tiamulin administered via drinking water significantly reduced the effects of S suis type-2 infection.

Free access
in Journal of the American Veterinary Medical Association

Abstract

OBJECTIVE

To determine whether passage of whole blood through a microaggregate filter by use of a syringe pump would damage canine erythrocytes.

SAMPLE

Blood samples obtained from 8 healthy client-owned dogs.

PROCEDURES

Whole blood was passed through a standard microaggregate filter by use of a syringe pump at 3 standard administration rates (12.5, 25, and 50 mL/h). Prefilter and postfilter blood samples were collected at the beginning and end of a simulated transfusion. Variables measured at each time point included erythrocyte osmotic fragility, mean corpuscular fragility, RBC count, hemoglobin concentration, RBC distribution width, and RBC morphology. In-line pressure when blood passed through the microaggregate filter was measured continuously throughout the simulated transfusion. After the simulated transfusion was completed, filters were visually analyzed by use of scanning electron microscopy.

RESULTS

Regardless of administration rate, there was no significant difference in mean corpuscular fragility, RBC count, hemoglobin concentration, or RBC distribution width between prefilter and postfilter samples. Additionally, there were no differences in in-line pressure during the simulated transfusion among administration rates. Echinocytes were the erythrocyte morphological abnormality most commonly observed at the end of the transfusion at administration rates of 12.5 and 25 mL/h.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested that regardless of the administration rate, the microaggregate filter did not alter fragility of canine RBCs, but may have altered the morphology. It appeared that the microaggregate filter would not contribute to substantial RBC damage for transfusions performed with a syringe pump.

Full access
in American Journal of Veterinary Research

Summary

We characterized the clinicopathologic manifestations of experimentally induced endotoxin-induced mastitis. Responses to hypertonic fluid therapy also were assessed. Eight cows received 1 mg of endotoxin by intramammary infusion in the left forequarter. Four hours after endotoxin administration, cows received 0.9% NaCl, 5 ml/kg of body weight (n = 4) or 7.5% NaCl, 5 ml/kg (n = 4) IV. Endotoxin-infused cows had expanded plasma volume, hyponatremia, transient hyperchloremia and hypophosphatemia, increased serum glucose concentration, and decreased serum activities of liver- and muscle-specific enzymes. Calculated plasma volume increased at 6 hours in cows receiving hypertonic NaCl, and at 12, 24, and 48 hours after endotoxin infusion in both groups. Concurrent observations of decreased serum protein concentration, erythrocyte count, and hematocrit supported observations of increased plasma volume. Relative plasma volume was greater in cows receiving hypertonic NaCl (124.3%) than in cows receiving isotonic NaCl (106.6%) at 6 hours after endotoxin infusion. Cattle receiving hypertonic NaCl had increased voluntary water intake after iv fluid administration. Increased water consumption was not accompanied by increased body weight, indicating probable occurence of offsetting body water loss. Serum sodium concentration in cows receiving hypertonic NaCl was increased 2 hours after fluid administration, but the magnitude of the change was minimal (< 4 mmol/L) and transient, indicating rapid equilibration with either interstitial or intracellular spaces. Serum sodium concentration was decreased in cows receiving isotonic NaCl at 12, 24, and 48 hours after endotoxin administration, compared with concentration prior to endotoxin adminstration, indicating selective loss of sodium.

Free access
in American Journal of Veterinary Research

Abstract

Case Description—A 1-year-old sexually intact female Netherland dwarf rabbit was examined because of a 3-week history of signs of lethargy, decreased appetite, left unilateral exophthalmia, a previous draining sinus from a left maxillary facial abscess, and bilateral nasal discharge.

Clinical Findings—The rabbit weighed 1.0 kg (2.2 lb) and had a body condition score of 1.5/5. Physical examination revealed generalized muscle atrophy, bilateral mucopurulent nasal discharge, and severe left-sided exophthalmia. Diagnostic investigation revealed anemia, neutrophilia, severe dental disease, a superficial corneal ulcer of the left eye, and a retrobulbar abscess.

Treatment and Outcome—Stomatoscopy-aided dental trimming, tooth removal, and abscess debridement were performed. Antimicrobials were flushed into the tooth abscess cavity, and antimicrobial treatment was initiated on the basis of cytologic findings and results of bacterial culture and susceptibility testing.Two months after the initial surgery, minimal exophthalmia was evident and no further physical, radiographic, or ultrasonographic changes were evident.

Clinical Relevance—Stomatoscopy is a valuable technique that can facilitate diagnosis, treatment, and serial reevaluation of rabbits with dental disease.

Full access
in Journal of the American Veterinary Medical Association

Abstract

OBJECTIVE To investigate the anti-inflammatory and immunomodulatory properties of tulathromycin in vitro and in experimental models of Actinobacillus pleuropneumoniae–induced pleuropneumonia and zymosan-induced pulmonary inflammation in pigs.

ANIMALS Blood samples from six 8- to 30-week-old healthy male pigs for the in vitro experiment and sixty-five 3-week-old specific pathogen–free pigs.

PROCEDURES Neutrophils and monocyte-derived macrophages were isolated from blood samples. Isolated cells were exposed to tulathromycin (0.02 to 2.0 mg/mL) for various durations and assessed for markers of apoptosis and efferocytosis. For in vivo experiments, pigs were inoculated intratracheally with A pleuropneumoniae, zymosan, or PBS solution (control group) with or without tulathromycin pretreatment (2.5 mg/kg, IM). Bronchoalveolar lavage fluid was collected 3 and 24 hours after inoculation and analyzed for proinflammatory mediators, leukocyte apoptosis, and efferocytosis.

RESULTS In vitro, tulathromycin induced time- and concentration-dependent apoptosis in neutrophils, which enhanced their subsequent clearance by macrophages. In the lungs of both A pleuropneumoniae– and zymosan-challenged pigs, tulathromycin promoted leukocyte apoptosis and efferocytosis and inhibited proinflammatory leukotriene B4 production, with a concurrent reduction in leukocyte necrosis relative to that of control pigs. Tulathromycin also attenuated the degree of lung damage and lesion progression in A pleuropneumoniae–inoculated pigs.

CONCLUSIONS AND CLINICAL RELEVANCE Tulathromycin had immunomodulatory effects in leukocytes in vitro and anti-inflammatory effects in pigs in experimental models of A pleuropneumoniae infection and nonmicrobial-induced pulmonary inflammation. These data suggested that in addition to its antimicrobial properties, tulathromycin may dampen severe proinflammatory responses and drive resolution of inflammation in pigs with microbial pulmonary infections.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To identify factors associated with abortions during early gestation classified as mare reproductive loss syndrome (MRLS).

Design—Case-control study.

Animals—324 broodmares from 43 farms in central Kentucky, including 121 mares from 25 farms that had early-term abortions (ETAs) associated with MRLS (case horses), 120 mares from the same farms but that did not abort, and 83 mares from 18 farms that were not severely impacted by MRLS.

Procedure—Farm managers were interviewed to obtain data on various management practices and environmental exposures for the mares. Data for case and control horses were compared to identify risk factors for mares having MRLS-associated ETAs.

Results—Several factors increased the risk of MRLS-associated ETAs, including feeding hay in pasture, greater than usual amounts of white clover in pastures, more eastern tent caterpillars in pastures, abortion during a previous pregnancy, and sighting deer or elk on the premises.

Conclusions and Clinical Relevance—Analysis indicates that certain characteristics of pastures predisposed mares to MRLS-associated ETAs. Methods for limiting exposure to pasture (keeping mares in stalls longer) during environmental conditions similar to those of 2001 (ie, sudden freezing in mid-April following warmer-than-usual springtime temperatures and larger-than-usual numbers of eastern tent caterpillars in and around pastures) should reduce the risk of mares having MRLS-associated ETAs. It was not possible to determine whether exposure to white clover or caterpillars were causal factors for MRLS or were merely indicators of unusual environmental conditions that resulted in exposure of mares to a toxic or infectious agent. (J Am Vet Med Assoc 2003;222:210–217)

Full access
in Journal of the American Veterinary Medical Association